Electric circuit breaker



March 24, 1942. l.. s. WALLE MATER/AL lnventor-z C s S- le, swf* b9 f HGAJEVOLv/NG /MsuLnT/A/G is Att car-neg.

l l l l l l Patented Mar. 24, 1942 2,217,422 ELECTRIC cmcU'rr nimmaLudwig' S. Walle, Lansdowne, Pa., assignmto General Electric Company, acorporation of New York Application March 8, 1940, Serial No. 322,9084

' 1'o claims." (61.200-151) My invention relates to electric circuitbreakers and more` particularly to arc-extinguishing devices for circuitbreakers of high interrupting capacity.

Within comparatively recent times and concomitant with variousdevelopments and improvements of apparatus of this general character,there has been an increasing tendency to employ air circuit breakers orthe like instead of oil circuit breakers in the construction ofelectrical generating stations, substations and associated equipment forthe generation and distribution of electric power. This is based largelyon the desire to eliminate oil from electrical equipment insofar aspossible so as to reduce the fire hazard y andl danger of explosions toa minimum.

Many vcircuit breakers have been proposed which eliminate the iirehazard due to oil by employing a iiuid blast, such as air or-other gas,for example, for arc-extinguishing purposes. As a general rule, thesecircuit breakers require a source of fluid pressure and associatedcontrol apparatus which greatly increases the expense and complicationof the apparatus. It would be desirable to have an electric circuitbreaker which eliminates the firey hazard associated with oil circuitbreakers and yet wherein no complicated means need be provided forproducing a source of uid under pressure which may be utilized forarc-extinguishing purposes.

Accordingly, it is an object of my invention to provide a new andimproved electric circuit breaker of high interrupting capacity which issimple and compact, utilizes a minimum number of moving parts, and whichis relatively inexpenthereby to` insure shorter arcing time, less dangerof restriking and therefore higher interrupting capacity.

Further objects and advantagesof my invention -will become apparent asthe following description proceeds and the features of novelty whichcharacterize my inventionwill be pointed out with particularity in theclaims annexedv to and forming a part of ythis specification.

For a better understanding of my invention, reference may be had to theaccompanying drawticularly to Fig. 1, I have illustrated a circuitbreaker embodying my invention contained in `a suitable insulatingcasing I0. This casing or housing may be constructed 'of any desirableinsulating material and may even comprise laminated wood or the like.rCasing I0 is provided with an insulating liner II which is made of amaterial from which gas is evolved under the in.-.

fluence of theheat of the arc drawn in the circuit breaker, which, atleast in part, aids in extinguishing the arc. Thisl liner may compriseinorganic materials, such as boric acid, ammonium alum, or organicmaterials, such as horn fibre and the like, or material formed of methylmethacrylate, as described and claimed in United States Letters PatentNo. 2,157,815, granted May 9, 1939, upon an application of Ralph V.Boyer, and assigned to the same assignee as the present invention.

The relatively movable contacts of the circuit breaker illustrated inFig. 1 comprise a pair of stationary electrodes or contacts I2 and I3suitably fastened to a pair of terminal members I4 and I5, respectively,which are iixedly mounted to insulating housing I0 by any suitable meansI6, and a movable horizontally positioned rod contact memberor electrodeI1 adapted to cooperate with fixed contacts I2 and I3, thereby providingtwo series breaks in the electric circuit when the circuit breaker isopened. Stationary contacts I2 and I3 are provided with contact tips I2' and I3', respectively, formed of an arc-resisting metal while movablerod contact member I1 is provided with contact tips IIa and IIb alsoformed of a suitable arc-resisting metal. The contact tips I2' and I3 ofthe respective xed contacts I2 and I3 are provided with slightlyinclined surfaces which cooperate with somewhat similar surfaces oncontact tips I'Ia and IIb of contact member I1 to insure good electricalcontact when the circuit breaker is closed. If desired `any suitable.well known wip ing means may be provided.

In order to produce relative movement between movable horizontallypositioned contact rod l1 including contact tips Ila and Ilb and iixedcontacts I2 and I3; I provide a barrier 2U of insulating materialvertically reciprocal in casing II) in a pair of slides formed bysuitable guide bars 2l fastened to the interior of housing I0. Barrier20 is adapted to pass through openings 22 and 23 in housing I0 and maybe con- `nected by means 24 to any suitable operating mechanism, `notshown, which may, for example, .comprise a suitable solenoid orspring-operating mechanism, or any other arrangement well known in thear't.

Rod contact member I1 is suitably mounted in xed relationship withvertically reciprocating barrier 20 by being supported in an insulatingtube 25 which passes through an opening formed in barrier 20 and issuitably attached to the latter. Upward movement of barrier 20 willcause a separation of rod contact I1 and associated xed contacts I2 andI3 to interrupt the electric circuit associated with terminals Il and I5oi the circuit breaker while closing of the circuit breaker isaccompanied by downward movement of 'barrier 20. y

In order to obtain high interrupting capacity of the circuit breaker aswell as a compact design, I provide cylindrical envelopes or bushings26a and 2Gb slidably mounted over the respective ends of rod contactmember I1 protruding from barrier 20. These sleeves or bushings 26a and2Gb are formed of a suitable gas-evolving material similar to that fromwhich liner II is formed. Sleeves or bushings 26a and 2Gb are shorterthan the associated portion of contact member I1 protruding from'barrier 2U and are provided with spring members 21a and 2lb,respectively, suitably mounted in a countersunk portion in bushings 26aand 26h for biasing said bushings away from barrier 2D so as to tend toenclose rod contact member I'I more completely. The lower edges ofsleeves 26a and 2Gb remote from barrier 20 are arranged in the downwardmovement thereof to engage with inclined surfaces IB' and I9 ofprotrusions I8 and I9 respectively which may be integral with insulatingliner Il so as to allow the contacting surfaces IIa and I 1b ofhorizontally positioned rod contact member I'I to extend beyond the endsof sleeve bushings 26a and 2Gb and protrusions I8 and I9 hold bushings26a and 2Gb in this retracted position when |the circuit breaker is inthe closed position illustrated in Fig. 1 so that electrical contactbetween arcing tips I'Ia, I'Ib and I2', I3' respectively. may be made.When barrier 20 is moved upwardly by suitable means, not shown, tointerrupt the electric circuit associated with terminals Il and I5 ofthe circuit breaker, spring means 21a and 21h force sleeves or bushings26a and 2Gb, respectively, away from barrier 20 and against the liner Ilof gas-evolving insulating material. When this occurs, contact II iscompletely enclosed in chambers formed by bushings 25a and 26h and linerII so as to be isolated from fixed contacts I2 and I3. The arcs drawnupon interruption of the circuit are snuffed out when the ends ofbushings 26a and 26h rub along insulating liner II and high-speedinterruption is obtained. The open condition of the circuit breaker isillustrated by the position'of contact member I1 and associated bushings26, shown dotted in Fig. 1. l

In order that the arc gases and arc products formed during theinterruption of the circuit may escape from casing or housing III,suitable exhaust ports 2B and 29, respectively. lare provided in housingI0 adjacent fixed contacts I2 and I3.

The operation of the circuit breaker will be obvious to those skilled inthe art in view of the detailed description included above. However,when the circuit breaker is in the position illustrated inl Fig. l.protrusions It and I9 of liner II hold bushings 26a and 2Gb against thetensions of their respective associated springs 21a and 2lb, wherebycontacting surfaces I1a and I 'Ib of rod contact Il may engage with thearcing tips IZ' and I3', respectively, of fixed contacts I2 and I3.Interruption of the circuit is obtained by moving barrier 2U upwardly,carrying movable rod contact I l along therewith, whereupon the electriccircuit is broken and an arc is drawn between arcing tips I2' and I laand I3' and IIb, respectively. Further upward movement of barrier 2liwill allow bushings 26a and 2Gb to move away from barrier 2D towardinsulating liner II. The heat of the arc will cause gases to be evolvedboth from liner il and from bushings 26a and 2Gb which will aid in theextinguishment of the arcs. Slidable movement of bushings or sleeves 26aand 26h will continue until the bushings are free from fixed contacts I2and I3, whereupon these bushings will rub against liners II snuiiing outthe arc and completely enclosing iixed contact member I'I in acylindrical chamber formed of an insulating material emitting anarc-extinguishing gas. The

open position of the circuit breaker is indicated in dotted lines inFig. 1 and, in view of the fact that contact member II is completelysurrounded by insulating material in this position, the separation ofthe contacts for isolating purposes need not be so great to preventrestriking of the arc as in prior art arrangements wherein one of thecontacts is not completely isolated from the other. This makes for amore compact arrangement. The arc gases formed during the circuitinterruption process are allowed to escape through exhaust ports 28 and29.

While I have shown a particular embodiment of my invention as applied toelectric circuit breakers, it will be apparent to those skilled in theart that my invention is not limited to the construction shown but thatchanges and modiiications may be made without departing from the spiritand scope of my invention and I aim in the appended claims to cover allsuch changes and modifications.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In an electric circuit breaker, the combination comprising a casing,a plurality of relatively movable contacts supported within said casing,means for producing relative movement between said contacts tn make orbreak the electric circuit associated with said circuit breaker, asleevelike bushing of gas-evolving insulating material movablypositioned on one of said contacts and arranged so as to allow said onecontact to protrude therefrom to engage another of said ccntacts duringthe closed circuit position of said circuit breaker, and means forcausing effective withdrawal of said one contact into said sleevelikebushing upon separation of said relatively movable contacts and forcausing said bushing to engage said casing so that high-speedinterruption of said circuit may be obtained.

2. In an electric circuit breaker including a casing, the combination ofa pair of relatively movable contacts associated with said casing, meansfor producing relative movement between said contacts to interrupt thecurrent in an associated electric circuit, a sleeve of gas-evolvinginsulating material movably positioned on one Aof said contacts andbiased so as to tend to extend beyond the end of said one contact, meansfor moving said insulating sleeve so that said one contact protrudestherefrom to engage with said other contact during the closed circuitposition of said circuit breaker, and means for allowing said biasingmeans to become effective upon separation of said relatively movablevcontacts to cause said sleeve to engage said casing so as to isolatecompletely said one contact whereby high-speed interruption of saidcircuit may be obtained.

3. In an electric circuit breaker, the combination comprising a pair ofrelatively movable contacts, means for producing relative movementbetween said contacts to interrupt the current in an associated electriccircuit, an insulating sleeve movably positioned on one of saidcontacts, a surface for limiting the vmovement of said sleeve byengaging with the end thereof adjacent the contacting portion` of saidone contact, said insulating sleeve being arranged so that said onecontact may protrude therefrom to engage said other contact during theclosed circuit position of said circuit breaker, and means for causingsaid insulating sleeve to engage said surface for snuiiing out the arcdrawn upon separation of i said relatively movable contacts.

4. In an electric circuit breaker, the combination comprising a pair ofrelatively movable contacts, a casing for` said contacts, means forproducing relative movement between said contacts to interrupt thecurrent in an associated electric circuit, an insulating sleeve movablypositioned on one of said contacts, a liner for said casing arranged toengage the end of said sleeve adjacentv the contacting portion of said.one contact when said first-mentioned means are operative, saidinsulating sleeve being arranged to allow said one contact to protrudetherefrom to engage said other contact during the closed circuitposition of said circuit breaker, and .means for causing said insulatingsleeve to engage said liner for snuillng out the arc drawn uponseparation of said relatively ,movable contacts.

5. In an electric circuit breaker, the combination of a casing, a pairof relatively movable contacts mounted within said casing, means forproducing relative movement between said contacts to interrupt thecurrent in an associated electric circuit, an insulating bushing movablypositioned on one of said contacts, the end ofwhich is adapted to bemoved against one of the walls of said casing to define a chamber withinsaid bushing, said bushing being positioned so that guished by thecombined snunlng action of said sheath and liner and thearc-extinguishing gas evolved therefrom.

'7. In an electric circuit breaker, the combination comprising a casing,a pair of relatively movable contacts supported within said casing,means for producing relative movement between said contacts to make orbreak the electric circuit associated4 with said circuit breaker, anenvelope of gas-evolving insulating -material movably positioned on oneof said contacts, a liner of gas-evolving insulating material for saidcasing for limiting the movement of said envelope by engaging with theend thereof adjacent the contacting portion of said one contact, saidenvelope being arranged so that said one contact may protrude therefromto engage said other contact during the closed 'circuit position of saidcircuit breaker, and spring means for biasing said envelope so as toengage said liner .upon separation of said relatively movable contacts,wherebythe arc drawn by such separation cauSes'gas to be evolved whichtogether with the snuing action of said envelope and liner rapidlyextinsaid contact protrudes therefrom in the closed circuit position oisaid circuit breaker, J and means for causing said contact to beenclosed f completely in said chamber upon separation of said relativelymovable contacts whereby interruption of said circuit is insured.

6. In anelectric circuit breaker, the combination comprising a casing, apair of relatively movable contacts supported within said casing, meansfor producing relative movement between said contacts to make or breakthe electric lcircuit associated with said circuit breaker, a sheath ofgas-evolving insulating material movably positioned on one of saidcontacts, a liner of gasevolving insulating material for said casing forlimiting the movement of said sheath by engaging with the end thereofadjacent the contacting portion of said one contact, said sheath beingarranged so that said one contact may protrude therefrom to' engage saidother contact during the closed circuitposition of said circuit breaker,and means for causing said sheath to engage said. liner upon separationof said relatively movable contacts whereby said arc is rapidlyextinguishes said arc.

. 8. In an electric circuit breaker, the combination comprising a pairof relatively movable contacts, a 'casing for said contacts, means forproducing relative movement between said contacts to interruptthecurrent in an associated electric circuit, an insulating sleeve movablypositioned on one of said contacts, and insulating means associated withsaid casing for causing movement of said `insulating sleeve uponengagement Withsaid last-mentioned means so as to allow said contact toprotrude therefrom to engage said other contact during the closedcircuit position of said circuit breaker.

9. In an electric circuit breaker, the combination comprising a pair ofrelatively movable contacts, a casing for said contacts, means forproducing relative movement between said contacts to interrupt thecurrent in an associated electric circuit, an insulating sleeve movablypositioned on one of said contacts and arranged to engage said casing tolimit movement in one direction thereof, said insulating sleeve beingarranged so that said one contact may protrude therefrom to engage saidother contact during the closed circuit position of said circuitbreaker, means for causing said insulating sleeve to engage said casving for snufng out the arc drawn upon separationof said relativelymovable contacts, and exhaust ports in said casing whereby the arcproducts during such circuit interruption may escape.

10. In an electric circuit-interrupting device including a casing, thecombination comprisinga pair cf arcing electrodes associated with saidcasing, a member of gas-evolving insulating material surrounding one ofsaid electrodes and adapted to engage said casing, said member beingmovable relatively to said one electrode under certain operatingconditions of said circuitinterrupting device, and means tending tocause said member to engage said casing to enclose said one electrodecompletely so that high-speed interruption of an arc between saidelectrodes may .be obtained.

LUDWIG S. WALLE.

